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How Dextromethorphan Helps Suppress Persistent Coughs

Sure, the physical effects of a cold — the headaches, the cough, interrupted sleep and raw sore throat — are unfortunately all too familiar. But the biological process behind a cough? That’s surprisingly complex. Dextromethorphan, the active ingredient in Delsym® cough medication, helps soothe a cough through a mechanism you might not expect. Read on to learn what actually happens when you cough, as well as how dextromethorphan helps you get some much-needed relief.

A Cough Starts at Your Nerve Endings

While you likely think of coughing as something that happens in your chest or throat, a persistent cough has a surprising amount to do with your nervous system. Your airways and lungs are packed with sets of nerves, which connect to your spinal cord and brain and transit information about what’s going on in your respiratory tract.

Some of these nerve endings detect harmful or irritating chemicals like ozone, a common component of air pollution. Other nerves, called mechanoreceptors, pick up physical changes in your lungs and airways. These mechanoreceptors detect if there’s fluid in your lungs, for example. They can also sense when there’s excess mucus or too much constriction in your respiratory tract — which can happen when you have an infection that causes a cough.

Triggering the Cough Reflex in Your Brain

Activated mechanoreceptors signal that something’s not right in your respiratory tract, but the nerves alone can’t trigger a cough. To do that, they send a chemical signal, which is picked up by special receptors in your brain, like a key fitting into a lock. Once enough mechanoreceptors send that signal (and enough “locks” have their “keys”) your brain initiates a reflex, sending a chemical message to your muscles that results in a cough.

How Dextromethorphan Fits in

Dextromethorphan works on the part of your brain responsible for the cough reflex, disrupting the communication between your brain and the nerves which provoke the coughing. It temporarily blocks the "lock" so that the "key" no longer fits. Without as many pro-coughing signals actually getting through to your brain (and fewer keys able to fit into their locks), you're less likely to reach the threshold needed for a cough reflex, and your persistent cough gets better or goes away. Time-release formulations — like Delsym® 12-Hour Cough Relief — keep your brain supplied with dextromethorphan or dextrorphan (primary metabolite of dextromethorphan) for 12 hours, raising your cough threshold long enough to get a good night's sleep or power through a busy day.

Combining Dextromethorphan with Other Therapies

While dextromethorphan alone is often enough to combat cough, it can also work in combination with other forms of medication to control coughing and congestion. Delsym® Cough+ Chest Congestion DM contains both dextromethorphan and guaifenesin, an expectorant. Guaifenesin helps to loosen and break up mucus in your airways, helping to get rid of chest congestion that otherwise might trigger your mechanoreceptors.

The result? Two-pronged cough protection: dextromethorphan to suppress the cough reflex in your brain and guaifenesin to help thin and clear mucus, a common coughing trigger in the first place. We bet you're breathing easier already.